[6BQ5]

I am starting to play around with a f/1.4 50mm SMC-A on my K-30 and it's a real challenge to get a controlled focus in my shots. It's my understanding that the plane in focus is razor thin and it's pretty hard for me to see it. When I see it and take the shot my composition ends up looking bad.

Is there a good authoritative reference I read through to get a better understanding of how to work with a fast lens? I am almost looking for something that would give me homework assignments!

Thanks!

[Rmel26]

Lucky you, K30 has focus peaking. This feature is quite new, first appearing in K01. If you are in low light environment, then you could use live view and focus peaking. Really good with manual lens. As you move the focus ring, you will actually see a band of shimmer which defines your focus plain. Experiment and take shots. Sometimes, the focus should be near the edge of this band.

[6BQ5]

I have tried focus peaking and I didn't like it because I couldn't understand it. The shimmer is ephemeral and I never know when the shimmer is at it's peak. Maybe I'm shooting in too bright of sunlight with too much contrast in my subject matter (i.e. long shadows, pre-dusk warm light, etc). I really miss my old split circle focus screen when I manually focus here.

[rbefly]

Hello Boris,
Like you, I had a very hard time focusing my 'M' and 'A' lenses on a DSLR. I was sure the problem with my eyesight and technique, until I started researching and found it's fairly common. There are several tips,tricks and aids, here's the four that helped me the most;
Dioptor Correction. Find a lens that focuses accurately on your camera body. Doesn't matter whether it's MF or AF. Set the camera on a tripod or solid base and focus on a contrasty subject, the front page of a newspaper or magazine works well.
Focus slowly and carefully until the lines are as sharp and clear as you can get. Now, carefully, without moving the camera or focusing ring, slowly click the diopter adjustment through it's range Most likely you'll find one or two positions that seem the sharpest..Take a photo of each adjustment that seems good, noting which adjustment goes with which photo.
Download the photos and enlarge. You will see clearly which adjustment is the absolute best. Make a note or mark of the adjustment position, that little slider gets jiggled quite easily! Remember, you can only focus as well as you can see.
Lens Correction; If one lens is particularly troublesome, it may need front-or-back focus correction. There are many free online DIY correction guides and others at a low cost. I purchased a lens focusing guide (looks like an eye chart) and color-correction chart online for $10.00 and it works fine Follow the directions for lens focus correction in your camera handbook. I have a 'cheat sheet' in my filter pack with the adjustment data for each lens that needed correction. Time-consuming, yes, but a big help!
Biggest Aid: A good viewfinder screen. Be prepared for a $75-$100 sticker shock. I use a split-prism Katzeye and recommend that brand, but there are others.
Last, an eyecup. These are about $5.00 online, I like the teardrop shape best but it is uncomfortable in the vertical position . The round type works in both camera orientations, but doesn't provide quite as much isolation from sidelight or backlight. To use it, you must remove the rubber cushion around the OVF.
Those are my tips, hope it helps!
Ron.

[EJMzagsfan]

I think that diopeter tip might help me a lot. It's something I havent thought of. Im doing it right now actually. Thanks.

[JimJohnson]

Actually the diopter is even easier to adjust than this.
Take the lens off and turn on the camera. Touch you shutter release to turn on the in-viewfinder LED display. Adjust the diopter until you see the sharpest characters. Done.

Wear multi-focal glasses? Remember this...

When you look at the LCD on the back side of the camera .... no matter how far away your subject might be, you need to focus on the LCD to see it. Use the close viewing part of your glasses.

When you look through the viewfinder ... no matter how far away your subject might be, you are actually looking at the focusing screen inside your camera - and the viewfinder optics are set to make this appear to be at infinity. Use the distance part of your glasses when you look through the viewfinder, NOT the closer focusing portion of your glasses. The diopter adjustment is there to tweak the view to infinity.

[6BQ5]

Thanks for all the tips!

I don't wear glasses and I got the viewfinder set up just fine. It took me a while because even when it is way out of focus my eye seemed to compensate for it by adjusting its own focus. The experience of watching a blurry image turn sharp on its own is surreal! I adjusted it to where my eye doesn't do this. It's pretty much in the center.

I looked up the focusing screen and I'm afraid of what I read about how it alters the exposure calibration. Sometimes it's +1, sometimes it's -1... all seems to depend on the specific piece of glass you get. My K-30 packaging mentions an optional interchangeable focusing screen available from Pentax. Is this one better to use? Would it alter the exposure calibration?

[JimJohnson]

Pentax's optional screens are identical to the original screen in terms of focusing. The difference is in the etched lines you see in the viewfinder to aid different composition needs.

[6BQ5]

Quick question: is there a way to change the calibration in my K-30 of when it thinks the image is in focus when using the viewfinder? It beeps and an OK signal illuminates saying that I'm in focus. This "in-focus" state has a place where it enter and where it leaves. Can I change the entry and exit points?

I ask because I took two quick shots of a newspaper at 45 degrees. My center focus point was marked off by a green dot. I imagine that the dot would be in the center of the focused area. That is, I should have just as much above the dot in focus as below it. My image turned out having quite a bit less in focus above the dot than below the dot.

My pictures were taken in a room at night and my illumination came from some fluorescent lights. This isn't the best set up. I know I need to do this during the day in sunlight and when I do this I will post some pictures.

[JimJohnson]

You are correct. The focus indicator isn't a specific point. Rather it has a range of what it thinks is acceptable focus.

My suggestion- fix the camera on a tripod. Set the lens' aperture wide open. Use LiveView and focus peaking to find the best focus point. Don't move anything. Place a piece of masking tape on the lens' focusing ring and mark the center focus mark.using a very fine tip felt pen.

Now switch off LiveView and verify the focus indicator is lighted. Move the focus ring each direction to find the edges where the focus indicator just lights. Mark those points on the tape. You now have some idea how far to continue turning the focus ring with that lens at that distance. Repeat the experiment at a couple distances to get a better feel for this lens. For good measure, always shoot at least one or two stops higher than wide open.

For what it is worth, I don't use the in-viewfinder focus indicator when I am focusing manually. I still trust my own eyes. At the point I can't trust my eyes, I will make a decision to A- use focus peaking, B- buy a viewfinder magnifier, or C- switch to a different focusing screen.

[Clavius]

No matter how many tips or tricks, manual focussing fast lenses through the OVF will always remain a big challenge. And it's easy to blame it on bad eyesight, I did that myself too, until I looked down the VF of the NEX7. The VF is bigger, brighter, better then any optical VF I've ever seen. You can zoom in for more accurate focussing, and use peak focussing if required.

That is what you'll have to resort to on you K-30. Peak focussing isn't for everyone. I myself find zooming in a much better solution.

[6BQ5]

Practice, practice, practice!

I have been practicing (and practicing... and practicing) my manual focusing skills with a SMC-A 50mm f/1.4 and a "cheap" Rikenon 35-70mm f/3.5 - 4.5.

The first thing I did was back off of f/1.4. Now I am between f/2 and f/3.5. My depth of field has increased slightly which subsequently increases my sharpness. I think at f/1.4 I was just "too fast" and it didn't suit my shooting style or my subjects.

The second thing I did was learn how to focus. I know, it sounds silly but focusing on the K-30 is way different than on a split screen film camera. I listen for the beep, I look for the little red dot, and I also look for the "in focus" entry and exit points to figure out where the center is. That center point seems to provide the best results. It took some training of my eyes too. I had to become much more critical of what I see through the viewfinder and question the camera's focus detection.

I thought I would share some of my results which I have posted on my Flickr account. Sometimes I "cheat" and drop down to f/5.6 but it's all in good fun.

[JimJohnson]

I know, it sounds silly but focusing on the K-30 is way different than on a split screen film camera.

Actually it would be the same if you used only the ground glass portion outside all the prism-based focusing aides on most film cameras. But I hear you, without those aides, it is much slower job.
If you makes you feel better, reducing the aperture by a stop or two typically improves lens sharpness in addition to increased DOF.

[narual]

It's my understanding that the plane in focus is razor thin

The power of math might be of assistance. But let someone else do it, because it's a pain.

Online Depth of Field Calculator
Depth of Field Table

On a 1.5x crop sensor, 50mm at f1.4, with the subject at 60 inches (5 feet) away, your depth of field is from 59 inches to 61 inches. That's about enough to get a face in focus if there's no tilt. At 1.8 you get another half inch. at 2.8 you get 4 inches.

Push out to 120 inches (10 feet) and you get a touch over 8 inches - from 116 inches to 124 inches. At 1.8 you get about 10 inches. At 2.8 it's 16 inches.

If your lens has focal distance markings, that can help. Try playing with it. Sometimes leaving things softly out of focus can look good. One of my favorite photos with a fast prime lens is this one where I had just a bit of hair in focus:

[scratchpaddy]

Dioptor Correction. Find a lens that focuses accurately on your camera body. Doesn't matter whether it's MF or AF. Set the camera on a tripod or solid base and focus on a contrasty subject, the front page of a newspaper or magazine works well.
Focus slowly and carefully until the lines are as sharp and clear as you can get. Now, carefully, without moving the camera or focusing ring, slowly click the diopter adjustment through it's range Most likely you'll find one or two positions that seem the sharpest..Take a photo of each adjustment that seems good, noting which adjustment goes with which photo.
Download the photos and enlarge. You will see clearly which adjustment is the absolute best.

I think there's a little bit of misunderstanding about the diopter here that I want to clarify. As JimJohnson said, it has nothing to do with your lens. If your diopter isn't right, it will make everything seem out of focus, or it will cause eyestrain as your eye tries to correct for it. It won't move the apparent focus point, though. It has nothing to do with focusing accuracy, beyond the fact that it can make the viewfinder difficult to see.

The focusing screen is exactly that: a screen. The lens is projecting an image onto it. In that image, the focal point is where it is. Your eyes can't change that any more than they can change the focal point of an image on a computer screen. If your diopter is off, the image will look blurry, but it won't make you think the camera is focusing somewhere it isn't.